In Marino et al. (2013) we provide revisited empirical calibrations for the oxygen abundances in HII regions based on the O3N2 and N2 indicators. This work is based on the most comprehensive compilation of both Te-based and multiple strong-line (ONS-based) ionized-gas abundance measurements in external galaxies to date in terms of all statistical significance, quality, and coverage of the parameters space. Our dataset compiles the Te-based abundances of 603 HII regions extracted from the literature but also includes new measurements from the CALIFA survey. We also present a comparison between our revisited calibrations with a total of 3423 additional CALIFA HII complexes with abundances derived using the ONS calibration. The O3N2 and N2 indicators can be empirically applied to derive oxygen abundances calibrations from either direct-abundance determinations with random errors of 0.18 and 0.16, respectively, and they show shallower abundance dependencies and statistically significant offsets compared to the classical calibrations (as the one of Pettini & Pagel (2004)).

The advent of the Hubble Space Telescope (HST) and the development of new photometric algorithms that take advantage of its stable observing platform above the atmosphere have allowed us to study the populations in globular clusters with very high precision.

The proof corrections supplied by the author were not made to the final version of the article (Guarnizo, Amendola, Kunz and Vollmer, 2015).

We apologise to the authors and to the readers for this omission.

After (2.6) on page 348, the statement “being S = AR.” should read

“being S = AR. and P1 = R/A.”

Improved versions of the figures are also presented below.

Context: we present a study of the central 200 pc of NGC 6951, in the optical and NIR, taken with the Gemini North Telescope integral field spectrographs, with resolution of ~ 0”.1 Methods: we used a set of image processing techniques, as the filtering of high spatial and spectral frequencies, Richardson-Lucy deconvolution and PCA Tomography (Steiner et al.2009) to map the distribution and kinematics of the emission lines. Results: we found a thick molecular disk, with the ionization cone highly misaligned.

The origin of the morphology-density relation is still an open question in galaxy evolution. It is most likely driven by the combination of the efficient star formation in the highest peaks of the mass distribution at high-z and the transformation by environmental processes at later times as galaxies fall into more massive halos. To gain additional insights about these processes we study the kinematics, star formation and structural properties of galaxies in Abell 2163 a very massive (~4×1015 M⊙, Holz & Perlmutter 2012) merging cluster at z = 0.2.

We use high resolution spectroscopy with VLT/VIMOS to derive rotation curves and dynamical masses for galaxies that show regular kinematics. Galaxies that show irregular rotation are also analysed to study the origin of their distortion. This information is combined with stellar masses and structural parameters obtained from high quality CFHT imaging. From narrow band photometry (2.2m/WFI), centered on the redshifted Hα line, we obtain star formation rates.

Although our sample is still small, field and cluster galaxies lie in a similar Tully-Fisher relation as local galaxies. Controlling by additional parameters like SFRs or bulge-to-disk ratio do not affect this result. We find however that ~50% of the cluster galaxies display irregular kinematics in contrast to what is found in the field at similar redshifts (~30%, Böhm et al.2004) and in agreement with other studies in clusters (e.g. Bösch et al.2013, Kutdemir et al.2010) which points out to additional processes operating in clusters that distort the galaxy kinematics.

The infrared channel of the Wide-Field Camera 3 on the Hubble Space Telescope revealed multiple main sequences of very low-mass stars in the globular clusters NGC 2808 and ω Cen. In this paper I summarize the observational facts and provide a possible interpretation.

We present the stellar populations properties of the interacting spiral NGC 5719, which is known to host two cospatial counter-rotating stellar discs.

We have discovered that Terzan 5, a stellar system in the Galactic Bulge, harbors two stellar populations with different iron content (Δ[Fe/H] ~ 0.5 dex) and possibly different ages. Moreover, the observed chemical patterns significantly differ from those observed in any known genuine globular cluster. These evidences demonstrate that, similarly to ω Centauri in the Halo, Terzan 5 is not a globular cluster, but a stellar system that was able to retain the gas ejected by violent supernova explosions. Moreover the striking chemical similarity with the Bulge stars suggests that Terzan 5 could be the relic of one of the massive clumps that contributed (through strong dynamical interactions with other pre-formed and internally-evolved sub-structures) to the formation of the Galactic Bulge.

In these last years a huge amount of both spectroscopical and photometric data has provided a plain evidence of the fact that Galactic globular clusters (GCs) host various stellar sub-populations characterized by peculiar chemical patterns. The need of properly interpreting the various observational features observed in the Color-Magnitude Diagrams (CMDs) of these stellar systems requires a new generation of stellar models properly accounting for these chemical peculiarities both in the stellar model computations and in the color - Teff transformations. In this review we discuss the evolutionary framework that is mandatory in order to trace the various sub-populations in any given GC.

We found stellar mass-dependent evolution of galactic molecular gas fractions ($f_{\rm mol}=\frac{M_{\rm mol}}{M_\star+M_{\rm mol}}$, Mmol: molecular gas mass, M*: stellar mass) where less massive galaxies have decreased fmol from z = 1 whereas massive galaxies have already had low fmol until z = 1. Comparison of the observed quantities (fmol, optical and near infra-red [NIR] colors, specific star formation rate [sSFR = SFR/M*]) with mass evolution models suggests that less massive galaxies had high fmol at z = 1 thanks to recent gas accretion.

DART-Ray is a 3D ray-tracing dust radiative transfer (RT) code that can be used to derive stellar and dust emission maps of galaxy models and simulations with arbitrary geometries. In addition to the previously published RT algorithm, we have now included in DART-Ray the possibility of calculating the stocastically heated dust emission from each volume element within a galaxy. To show the capabilities of the code, we performed a high-resolution (26 pc) RT calculation for a galaxy N-body+SPH simulation. The simulated galaxy we considered is characterized by a nuclear disc and a flocculent spiral structure. We analysed the derived galaxy maps for the global and local effects of dust on the galaxy attenuation as well as the contribution of scattered radiation to the predicted observed emission. In addition, by performing an additional RT calculation including only the stellar volume emissivity due to young stellar populations (SPs), we derived the contribution to the total dust emission powered by young and old SPs. Full details of this work will be presented in a forthcoming publication.

Increasing number of massive globular clusters (GCs) in the Milky Way are now turned out to host multiple stellar populations having different heavy element abundances enriched by supernovae. Recent observations have further shown that [CNO/Fe] is also enhanced in metal-rich subpopulations in most of these GCs, including ω Cen and M22 (Marino et al. 2011, 2012). In order to reflect this in our population modeling, we have expanded the parameter space of Y2 isochrones and horizontal-branch (HB) evolutionary tracks to include the cases of normal and enhanced nitrogen abundances ([N/Fe] = 0.0, 0.8, and 1.6). The observed variations in the total CNO content were reproduced by interpolating these nitrogen enhanced stellar models. Our test simulations with varying N and O abundances show that, once the total CNO sum ([CNO/Fe]) is held constant, both N and O have almost identical effects on the HR diagram (see Fig. 1).

We discuss the yields from Asymptotic Giant Branch stars, depending on their mass and metallicity. In agreement with previous investigations, we find that the extent of Hot Bottom Burning increases with mass. The yields of models with chemistry typical of high–metallicity Globular Clusters, i.e. Z = 0.008, show only a modest depletion of magnesium, and an oxgen depletion of ~ 0.4 dex. Low–metallicity yields show a much stronger magnesium depletion, and a dramatic drop in the oxygen content, ~ 1.2dex smaller than the initial value. We suggest that the Globular Cluster NGC 2419 is a possible target to the hypothesis of the self–enrichment scenario of Globular Clusters by the winds of Asymptotic Giant Branch stars.

We have collected optical integral field spectroscopic data for M31 with the spectrograph VIRUS-W that result in kinematic maps of unprecedented detail. These reveal the presence of two kinematically distinct gas components.

The results of numerous spectroscopic and photometric studies have revealed the presence of multiple stellar populations in many globular clusters. In this paper we summarize the results of our recent studies on the dynamical evolution of multiple-population clusters, the implications of the structural properties of multiple-population clusters for the evolution of binary stars, and the possible contribution of globular clusters to the assembly of the Galactic halo.

We report on first molecular gas observations in the Lyman Alpha Reference Sample (LARS; Hayes et al.2013, 2014, Östlin et al.2014), which were performed using the 45m telescope at the Nobeyama Radio Observatory (NRO). The beamsize at the observed 12CO (1–0) emission is ≈ 15” corresponding to ≈ 12kpc at the given redshift of z ≈ 0.04. We detected strong 12CO emission in LARS 3 (Arp 238), marginally detected LARS 8 (SDSS 1250+0734) and derived an upper limit for LARS 9 (IRAS 08208+2816).

We present stellar mass maps for the S4G sample based on imaging at 3.6 μm that we correct for the presence of non-stellar emission using an ICA technique. Our dust-free images can be readily converted into stellar mass maps, and this important legacy dataset will be made public through IRSA.

We numerically investigate the formation processes of globular clusters (GCs) in gas-rich dwarf galaxies at high redshifts. Our particular focus is on how the first and second generations of stars can be formed from high-density gas clouds in dwarf galaxies. We find that massive stellar clumps first form from massive gas clumps that are developed from local gravitational instability in gas-rich dwarfs. These stellar clumps with masses larger than ~ 2 × 106 M⊙ can finally become the first generation of stars in GCs. After supernova explosion expels the remaining gas in the clumps, stars can form from eject of AGB stars that is accreted onto the central regions of the clumps (i.e., first generation of stars). The compact clusters of these stars have much higher densities and a significant amount of internal rotation (~ 5 km s−1) in comparison with the first generation and thus correspond to the second generation.